Aliens. For real this time.

[Alex]

If you believe in God as an entity that would not "have to work within the set of rules He created" then there is no such thing as proof of evolution.

I don't think they yet have a real sense of timeline, but absent a "creator" is unlikely that the bacteria have been there as long as the lake has. It is less than a million years old and it may not always have been so alkaline and heavy in arsenic (it was significantly bigger during the last ice age and was possibly part of a much larger body of water even earlier.

The bacteria are gentically similar to other known bacteria so they are not an entirely independent evolutionary track. Yes, if the report is correct (there has been some criticism of the research, though I'm not remotely expert enough to have a clue how valid it is) it is evidence of evolution but then even most creationists don't deny bacterial adaptation since lesser changes can be observed in something resembling real time (it is at the more macro that the get fidgeting starts).